Electric induction device



Sept 5 1950 R. T. REARDQN ,52h53 Emc'mxc .INDUCTION DEVICE Filed zum 5,194e Inventor-z @Obert T Reardon.,

His Attorney.

Patented Sept. v5, 1950 ELECTRIC INDUCTION DEVICE Robert T..Reardon,Fort Wayne, Ind., assignor to General Electric Company, a corporation ofNew York Application J une 5,

1 claim. 1

This invention relates to electric induction devices and moreparticularly to transformers and reactors.

It is often necessary, particularly in circuits which contain gaseousdischarge lamps having negative resistance characteristics, to utilizesome means of limiting the circuit current. This may be done by theaddition of resistance to the circuit but the usual method, resulting ingreater economy, is to use a current limiting reactor. This may be aninductive device which has high leakage reactance resulting in anincreased voltage drop as the current drawn through the deviceincreases. It is customary to incorporate, since higher-than line`voltages may be necessary for the operation of gaseous discharge lamps,this high reactance in a step-up transformer resulting in a highreactance current limiting transformer. In the conventional highreactance transformer construction the high leakage ux is achieved byproviding a low reluctance leakage path utilizing magnetic shuntsbetween the primary and secondary coils. l

In accordance with the particular-application of this invention setforth here the use of the magnetic shunts to provide a low reluctanceleakage path is eliminated by winding either the primary or secondarycoils of the transformer, or both, of wire which is formed of twomaterials; one a low resistance material such as copper and the other amagnetic material such as iron. In this manner the high reluctance ofthe air path which would normally be transversed by the leakage flux isdecreased by the presence of the magnetic material in the winding. Itshould be noted that only a portion of the primary or secondary windingsneed be wound with this specially prepared wire.

It is an object of this invention to provide a new and simple highreactance transformer construction which eliminates the use of magneticshunts.

It is another object of this invention to provide l a new and simplehigh reactance transformer construction which achieves a low reluctanceleakage path by utilizing a coil winding which possesses magneticproperties'.

Still another object of this invention is to provide a new and simplehigh reactance transformer construction which has primary or secondarycoils, or both. wound entirely or partially of wire which is formed fromtwo materials; one presenting high electrical conductivity and the otherpresenting high magnetic conductivity.

A further object of this invention is to provide 1948, Serial No. 31,347

a new and simple induction apparatus which occupies less space than theusual device.

The invention will be better understood from the following descriptiontaken in connection 5 with the accompanying drawing and its scope willbe pointed out in the appended claim.

In the drawing Fig. 1 is a plan view of a particular embodiment of theinvention as applied to the construction of a luminous tube transformerand ballast. Fig. 2 is a cross sectional view taken through the primarycoil of the transformer and ballast shown in Fig. 1.

Referring now to the drawing, there is shown in Fig. l, by way ofexample, a luminous tube transformer and ballast I having a primary coil2 and secondary coils 3 and 4 prepared in accordance with thisinvention. The transformer coils 2, 3 and 4 are mounted on a magneticcore E which presents a low reluctance ux path and are separated fromthe core 5 by the insulation 6. In Fig. 2, the cross sectional view ofthe primary winding 2 of the transformer and ballast i shown in Fig. 1,the primary coil 2 is wound from a preferred form of wire having anouter section I formed from a magnetic material having a relatively highelectrical resistivity and a center section 8 formed from a highlyconductive material having a low magnetic permeability. Thus the wiremay, for example, have an outer iron section l formed on a copper core8. It should be noted that either the primary coil 2 or the secondarycoils 3 and 4 or primary and secondary coils or portions thereof may beprepared from this preferred form of wire.

As can be seen in Fig. 1, the disposition of the transformer coils 2, 3and 4 is such that the secondary coils 3 and 4 are mounted on themagnetic core' 5, one on either side of the primary coil 2. In theconventional form of luminous tube transformer and ballast, magneticshunts are interposed between the primary coil and the secondary coil insuch a manner as to present a low reluctance leakage flux path. Thetransformer I construction disclosed by this invention achieves a highreactance ballasting eiect by the use of a low reluctance leakage fluxpath andin so doing eliminates the magnetic shunts which are normallypresent. The shunts are, in effect, replaced by the magnetic outersurface 'l of the wire from which, in the illustrated case, the primarycoil 2 is wound. A leakage path, as shown by the lines 9 in Fig. 2, isformed by the magnetic surface of the wire and, therefore, a substantialamount of iiux produced by current flow in the 55 primary 2 is notutilized in linking the primary and secondary coils 2, 3 and 4. Sincethe shunts are eliminated a more compact ballast and transformer I,which is important from the commercial standpoint, may be constructed.

While there has been shown and described a particular embodiment of thisinvention, it will be obvious to those skilled in the art that variouschanges and modifications can be made therein without departing from theinvention and, therefore, it is aimed in the appended claim to cover allsuch changes and modiications as fall within the true spirit and scopeof the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

In an electric transforming device atleast one primary coil member andone secondary coil member mounted on a magnetic core member and beinginsulated therefrom, said magnetic core member presenting asubstantially closed magnetic path, at least one of said coil membershaving a L plurality of contiguous turns constructed of wire formed fromtwo different materials, said wire aillxed thereto, said copper and saidiron being conductively connected in parallel. said iron sheath ofcontiguous turns of said wire being in. contact so as to establish withsaid core l. relatively low reluctance substantially closed lelhle fluxpath of magnetic material.

ROBERT T. REARDON.

REFERENCES crrlm The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Date Number Name 1,306,815 Houchin June 17, 19191,406,002 Goodman Feb. 7, 1922 1,406,328 Atherton Feb. 14, 19221,792,756 Osnos Feb. 17, 1931 1,836,615 Owen Dec. 15, 1931 1,972,319Rypinskl Sept. 4, 1934 2,075,906 Maude Apr. 8, 1937 2,223,737 Moses Dec.3, 1940

